renal mixed epithelial and stromal tumor

Definition: Mixed epithelial and stromal tumors are uncommon biphasic tumors of the kidney, with cystic and solid areas composed of a morphologically diverse stroma, including ovarian-like stroma and an epithelial component with considerable heterogeneity. Little is known about the histogenesis and clonal origins of these tumors.

Images

 Mixed epithelial and stromal tumor of the kidney (MEST)

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Some data support the theory that the stroma and epithelium arise from a common cell of origin. (21753695)

MEST represents a tumour developing from mullerian-like stromal cells in the kidney. MESTs in males were histopathologically slightly different from those in females due to the different hormonal milieu.

Cystic nephroma (CN) and mixed epithelial and stromal tumor (MEST) are rare benign renal neoplasms that have overlapping clinical and morphologic features, including predominance in middle-aged women, variably cystic architecture, eosinophilic cells, and hobnail cells lining the cysts and ovarian-type stroma. For both entities, a unifying term of "renal epithelial and stromal tumor" (REST) to encompass the spectrum of findings observed in these tumors.

Synopsis

 In females, the stromal component showed areas of mullerian differentiation with positive immunoreactivity for oestrogen (ER) and progesterone receptors (PR) and CD10.
 features of mullerian epithelium and reactive renal tubular cells in the epithelial component
 fibrous and smooth muscle stroma and cysts lined only by reactive renal tubular cells
 The neoplastic stroma encroaches on the renal tubules and has the potential to stimulate the growth of the renal tubules by contact, with development into cysts.

 The mullerian stroma likely induces the renal tubules to differentiate into mullerian-like epithelium.

 possible melanocytic differentiation (HMB45+)

Differential diagnosis

 cystic nephroma which represents an incidence of 1.6% of renal neoplasms in adults.

References

 Cystic nephroma/mixed epithelial stromal tumor: a benign neoplasm with potential for recurrence. Sun BL, Abern M, Garzon S, Setty S. Int J Surg Pathol. 2015 May;23(3):238-42. doi : 10.1177/1066896914563391 PMID: 25525149

 Mixed epithelial and stromal tumors of the kidney: evidence for a single cell of origin with capacity for epithelial and stromal differentiation. Kum JB, Grignon DJ, Wang M, Zhou M, Montironi R, Shen SS, Zhang S, Lopez-Beltran A, Eble JN, Cheng L. Am J Surg Pathol. 2011 Aug;35(8):1114-22. PMID: 21753695

 Malignant mixed epithelial and stromal tumor of the kidney with rhabdoid features: report of a case including immunohistochemical, molecular genetic studies and comparison to morphologically similar renal tumors. Sukov WR, Cheville JC, Lager DJ, Lewin JR, Sebo TJ, Lewin M. Hum Pathol. 2007 Sep;38(9):1432-7. PMID: 17707262

 Mixed epithelial and stromal tumour (MEST) of the kidney: report of 14 cases with male and PEComatous variants and proposed histopathogenesis. Mai KT, Elkeilani A, Veinot JP. Pathology. 2007 Apr;39(2):235-40. PMID: 17454754

 Cystic nephroma and mixed epithelial and stromal tumor of kidney: a detailed clinicopathologic analysis of 34 cases and proposal for renal epithelial and stromal tumor (REST) as a unifying term. Turbiner J, Amin MB, Humphrey PA, Srigley JR, De Leval L, Radhakrishnan A, Oliva E. Am J Surg Pathol. 2007 Apr;31(4):489-500. PMID: 17414095

 Metanephric adenoma mimicking papillary carcinoma arising in a mixed epithelial and stromal tumor of the kidney. Iqbal J, Gupta S, Breuer FU. Cancer Genet Cytogenet. 2006 Oct 1;170(1):83-5. PMID: 16965964

 Mixed epithelial and stromal tumor of the kidney. Adsay NV, Eble JN, Srigley JR, Jones EC, Grignon DJ. Am J Surg Pathol. 2000 Jul;24(7):958-70. PMID: 10895818